Table 1.
Comparison of Metformin Users and Nonusers Hospitalized With Pneumonia
| Variables | Metformin (n = 7039) | No Metformin (n = 27 720) | P |
|---|---|---|---|
| Demographics | |||
| Age, mean (SD), years | 74.9 (6.6) | 77.3 (7.1) | <.0001 |
| Male | 6945 (98.7%) | 27 325 (98.6%) | .6 |
| Race | |||
| White | 5839 (83.0%) | 21 993 (79.3%) | <.0001 |
| Black | 691 (9.8%) | 3698 (13.3%) | <.0001 |
| Hispanic | 537 (7.6%) | 2236 (8.1%) | .2 |
| Nursing home residence | 105 (1.5%) | 562 (2.0%) | .003 |
| Socioeconomic proxies | |||
| VA priority group 1 | 1600 (22.7%) | 6651 (24.0%) | <.0001 |
| VA priority groups 2–6 | 4693 (66.7%) | 18 549 (67.0%) | |
| VA priority groups 7–8 | 746 (10.5%) | 2520 (9.1%) | |
| No. of outpatient visits the year prior to admission, mean (SD) | 18.0 (14.1) | 18.9 (14.6) | <.0001 |
| Characteristics of hospitalization | |||
| ICU admission | 1217 (17.3%) | 5260 (19.0%) | .001 |
| Invasive mechanical ventilation | 473 (5.3%) | 1632 (5.5%) | .009 |
| Noninvasive mechanical ventilation | 370 (5.3%) | 1512 (5.5%) | .5 |
| Vasopressors | 349 (5.0%) | 1577 (5.7%) | .002 |
| Guideline-concordant antibiotics | 5842 (83.0%) | 22 193 (80.1%) | .001 |
| Comorbid conditions | |||
| Tobacco use | 3039 (43.2%) | 10 498 (37.9%) | <.0001 |
| Alcohol abuse | 194 (2.8%) | 940 (3.4%) | .007 |
| Illicit drug abuse | 78 (1.1%) | 361 (1.3%) | .2 |
| Myocardial infarction | 515 (7.3%) | 2732 (9.9%) | <.0001 |
| Heart failure | 1668 (23.7%) | 10 274 (37.1%) | <.0001 |
| Peripheral vascular disease | 1242 (17.6%) | 6162 (22.2%) | <.0001 |
| Stroke | 1241 (17.6%) | 6460 (23.3%) | <.0001 |
| Chronic obstructive pulmonary disease | 3474 (49.4%) | 143 473 (48.6%) | .3 |
| Rheumatologic disease | 146 (2.1%) | 755 (2.7%) | .002 |
| Mild liver disease | 36 (0.5%) | 252 (0.9%) | .001 |
| Peptic ulcer disease | 164 (2.3%) | 769 (2.8%) | .04 |
| Dementia | 222 (3.2%) | 1433 (5.2%) | <.0001 |
| Diabetes | 6964 (99.0%) | 27 183 (98.1%) | <.0001 |
| Diabetes with complications | 1950 (27.9%) | 8840 (31.9%) | <.0001 |
| Hemiplegia | 103 (1.5%) | 467 (1.7%) | .2 |
| Renal disease | 430 (6.1%) | 8891 (32.1%) | <.0001 |
| Any prior malignancy | 265 (3.8%) | 1084 (3.9%) | .6 |
| Metastatic solid tumor | 1616 (23.0%) | 6436 (23.2%) | .6 |
| Hematologic malignancy | 167 (2.4%) | 673 (2.5%) | .8 |
| HIV | 4 (0.1%) | 23 (0.1%) | .5 |
| Other medications | |||
| Antipsychotic agents | 462 (6.6%) | 1655 (6.0%) | .023 |
| Antiplatelet agents | 766 (10.9%) | 3238 (11.7%) | .05 |
| Statins | 4140 (58.8%) | 12 171 (43.9%) | <.0001 |
| ARBs | 810 (11.5%) | 2671 (9.6%) | <.0001 |
| ACE inhibitors | 4008 (57.0%) | 11 183 (40.3%) | <.0001 |
| Antiarrhythmics | 228 (3.2%) | 987 (3.6%) | .2 |
| B-Blockers | 3282 (46.6%) | 11 262 (40.6%) | <.0001 |
| Calcium channel blockers | 2308 (32.8%) | 8289 (29.9%) | <.0001 |
| Diuretics | 4317 (61.3%) | 16 005 (57.7%) | <.0001 |
| Oral antidiabetic medications | 5832 (50.9%) | 8988 (32.4%) | <.0001 |
| Nitrate antianginal medications | 1339 (19.0%) | 5996 (21.6%) | <.0001 |
| Other antihypertensive medications | 1767 (25.1%) | 7067 (25.4%) | <.0001 |
| Insulin 90 days prior | 1684 (24.0%) | 8612 (31.1%) | <.0001 |
| B-Agonist bronchodilators | 2538 (36.1%) | 8616 (31.1%) | <.0001 |
| Theophylline | 214 (3.0%) | 650 (2.3%) | .003 |
| Other cardiac medications | 5908 (83.9%) | 21 295 (76.8%) | <.0001 |
| Other inhaled medications | 1813 (25.8%) | 5784 (20.9%) | <.0001 |
| Other injectable medications | 395 (5.6%) | 1535 (5.5%) | .9 |
| Oral corticosteroids | 1351 (19.2%) | 5117 (18.5%) | .4 |
| Other pulmonary medications | 2461 (35.0%) | 8184 (29.5%) | <.0001 |
| Other bronchodilators | 2708 (38.4%) | 9340 (33.7%) | <.0001 |
| Antibiotics within 90 days prior to hospitalization | 1984 (28.2%) | 7509 (27.1%) | .07 |
Data are presented as no. (%) unless otherwise indicated. Abbreviations: ACE, angiotensin-converting enzyme; ARB, angiotensin II receptor blocker; HIV, human immunodeficiency virus; ICU, intensive care unit; SD, standard deviation; VA, Veterans Affairs.